1. Field of the Invention
The present invention generally relates to wireless telecommunications, and more specifically, relates to a system and method for transmitting alert tones in a push-to-talk system on a wireless network to identify speakers in group communications.
2. Description of the Related Art
Technology advancement has made mobile telephones or wireless communications devices cheap and affordable to almost everyone. As the wireless telephones are manufactured with greater processing ability and storage, they also become more versatile and incorporate many features including the direct radio communication capability between two or more individual handsets. This direct radio communication capability is commonly known as the push-to-talk (PTT) or “walkie-talkie” feature that allows a user with one handset to communicate with a predefined set of members of a group without dialing a destination telephone number.
In a PTT system, a handset uses one single frequency for both upward and downward communications with a remote server, while in a normal wireless communication a wireless telephone uses two frequencies for communicating with the server, one for upward and one for downward communications. The PTT system requires the person who is speaking to press a button while talking and then release it when he is done. Any listener in the group can then press their button to respond. In this manner, the system can determine which direction the signal should be traveling in. When a user makes a call to a receiving party or a group of receiving parties using the PTT system, the user's handset first makes a request to a remote server. The remote server verifies that no other party is using the communication channel and the channel is available then assigns the channel to the user. The user's message is received by the server and the server duplicates the message for each and every receiving party. After the message is transmitted to every receiving party, the channel is released and ready for use by other parties.
The PTT system relies on cellular technology to connect to the recipient devices. Conversely, a normal “walkie-talkie” style two-way radio will only operate if the radios are within a certain distance of each other. Systems using the PTT feature can communicate anywhere within a service area specified by its service provider, typically a large urban area or even nationally.
Generally, in a communication through the PTT feature one user broadcasts his messages to a plurality of members in his PTT communication group and the message is broadcasted without any identification of the speaker unless the user identifies himself every time he sends an audio message to his PTT communication group. The listening members in the PTT communication group have to identify the speaker by his voice or manner of speaking and in a large PTT group confusion often occurs because of misidentification of the speaker.